Guard and accident prevention equipment for wood working industry



May 4, 1965 L. K NTOR GUARD AND ACCIDENT PREVENTION EQUIPMENT FOR WOOD WORKING INDUSTRY Filed May 29, 1963 so 32 31 29 7 14 24 16a 230 295226 6 3a 7 a o 4 z 9 1011 9 78a Fig.4

United States Patent 3,181,579 GUARD AND ACCIDENT PREVENTION EQUE- MENT FOR WOOD WORKING INDUSTRY Laszl Kantor, Budapest, Hungary, assiguor to Technoimpex Magyar Gepipari Kulkereskedelmi Vallalat,

Budapest, Hungary, a firm Filed May 29, 1963, Ser. No. 284,172 4 Claims. (Cl. 144-251) This invention relates to safety guard and accident prevention equipment for planing and surface planing machines used in the wood working industry.

From the aspect of accident hazards, the surface planing machine is the most hazardous among machines used in the wood working industry. The hazard of these machines lies in the fact that in operation, the blades are fully exposed and hence the operators hand may easily come into contact with the rotating blades. Statistical records reveal that approximately 50% of accidents occurring in the wood working industry are caused by surface planing machines. Many attempts have been made over a long period to evolve a suitable type of safety guard for these machines and as a result numerous guards have been developed and are in use, but none of these provide a perfect or even adequate degree of safety.

The earliest solution was a cover made either of metal or of wooden laths strapped together, and placed over that part of the blades which was inoperative. Later and more widely used methods provide a sheet metal cover protection operated by spring or counter weight, automatically raised and opened by the workpiece as it is drawn over the blades and automatically closing again as the workpiece passes from the rotating blade area. This method has, however, not yet been suitably developed for practical works usage as an open gap remains either preceding or following the workpiece, and often in both cases, with resultant danger of the hand inadvertently touching or slipping against the blades. In actual use, this method proves to be more dangerous than no guard at all, as the operator falls into the habit of relying on the guard which does in fact not provide protection. As a result of such shortcomings, this type of guard has not been produced for large works scale application.

Another type of protective device which has been developed for the prevention of accidents utilizes arched lower and upper protecting covers closing over a blade shaft from both sides thereof and alternating for the full width of the table. Such protecting covers are tiltable to a position beneath the table and appear to provide the vmost satisfactory results. Such devices also include a series of double armed opening levers simultaneously spreading over the full width of the table and tiltable to a position under the table on the feed side of the blade shaft. Such a device is shown in US. Fatent No. 1,829,- 313. However, such devices do not provide the maximum degree of safety.

Accidents occurring at wood working machines are caused however not only by the cutting blades, but also by work pieces violently repelled by the blades. None of the types known in use or from descriptions or patent specifications are capable of eliminating the above hazards, and additionally their operation is cumbersome and impedes work, hence in most cases machine operators tend to discard or disengage the guards. The main disadvantage of all types recommended or used heretofore is that they can be opened by hand or that the blades remain exposed after passing the workpiece over the blade shaft. Thus in pushing the workpiece for the final cut, the operators hand may slip off onto the rotating blades. Such occurrence is further facilitated by the impetus increase arising as the cutting resistance ceases, thereby imparting additional movement to the hand pushing the ice workpiece, and it is just at this critical moment that the existing guard types fail to offer protection.

Wood working industry literature acknowledges that a full degree of protection is not provided by a guard consisting of a sheet metal lath and coil spring assembly placed above the blade system, and that at present no really effective protection equipment exists.

The invention finally eliminates the drawbacks of an earlier proposed guard type which not only failed to provide adequate protection but also caused breakdowns with work-pieces below a defined thickness. With thicknesses of l%" and below, the workpiece penetrated beneath and became jammed under the covers forming the guard and in breadth, the workpiece jams between the fence lath and the components forming the guard. These disturbances tend to detract the attention of the operator and irritate him, thus increasing the accident hazard.

This invention is free from these defects and forms a simple equipment offering full protection against accidents. Essentials of the invention are a guard made up of curved elements connecting to the table top and completely covering one side of the blade shaft from end to end, while on the other side of the shaft a similar guard assembly overlaps the first guard, so that the two together provide a double guard in front of and behind (both sides) the blade shaft; opening and closing of the double guard is performed automatically by the workpiece itself in such a manner that the wood to be planed, i.e. the workpiece, pedalwise actuates a tilting lever which opens the front part of the guard assembly, and as the front edge of the workpiece reaches the blades it pushes forward the other part of the assembly, then, as the workpiece passes over the blades, the assembly components closely follow the end of the workpiece, fully covering the blade shaft with the continuous guards; additionally, a locking lever actuated by the workpiece is provided and only when this is released, can the workpiece proceed to wards the blade shaft, opening the guard assemblies as it travels. The cutting blades remain inaccessible to the hand during the whole cycle of openations.

Due to the divided arrangement of the guard elements, only that part of the blade shaft length becomes uncovered which actually processes the workpiece, which itself covers the exposed section of the blade shaft, until the guard elements passed by, closely follow the workpiece and close over the blade shaft.

Furthermore, the invention provides for a workpiece guiding rail adjustable laterally and fixably in its adjusted position, the guiding ra-il being disposed at one edge of the table, parallel to but slightly spaced from the protecting element.

The invention is dealt with more fully in the following description and the accompanying drawings showing an application example of the invention. FIGS. l-3 are transverse sections of the surface planing machine through the blade shaft, showing the guard equipment in three different working positions and FIG. 4 is a plan view of the position shown in FIG. 1.

The drawings show only those parts of the planing machine necessary for illustration of the invention: the bladeshaft 1, machine frame 2, feed-side 3a and delivery side 3b of the machine table, adjustable for elevation in the usual manner by handwheel 4 and screw shaft (FIGS. 1-3), and fence lath 5 displaceable perpendicularly or obliquely to the axis of the blade shaft (FIG. 4).

FIG. 1 shows a workpiece 6 placed on the feed-side 3a of the machine table, ready to be pushed by the operator downwards and forwards towards the blade shaft 1.

On the rear or run-off side, blade shaft 1 is directly covered by the curved guard elements 7 placed in a row similar to piano keys, over the entire length of the blade 3 shaft. The curved guard separately in the comb-like recesses 8 formed in the edge of the run-off table by the side of the blade shaft (FIG. 4,).

a curved sheet metal plate 8b running the full width of the table and length of'the blade shaft. The guard elements 7 are guidedby the dividing walls 8aand move between the ribs separatingopenin'gsS, movement being imparted by weights '9 attachedto' one end of rods 11, these acting as two-armed leversturning on shaft 10,

while the other end of these levers is swivel-jointed by pins 12 to the individual curved guard elements 7 (FIG. 1).. In'their position covering blade shaft 1, the curved 'guard'e1ements7 as fshown on FIG. 1, extend over to the feed edge 3c along 'the blade shaft on table top 3a (FIG. 2), closely sealing of? the blade area, so that these alone providean arched guard securely covering the blade a shaft. The swivelpath of the two-armed lever 11, limits movement of curved elements 7 in the closed position (FIG. 1) by limit stop 13, and in the open positio (FIG. 3) by limit stop 13a.

A second guard assembly consisting of a piano keylike series of curved elements 14 on the feed table side of the blade shaft, extends over the first guard elements 7 from the front; these curved elements 14 move in openings provided with a step 15 commencement, formed in are swivel-jointed by pins 17 to one end of'the two-armed levers 19 which swing on shaft 18 and to which movement is imparted by weights 20 fitted to the other end. Levers 19 are swivel-jointed by means of rods 21to twoarmed levers 23 turning on shaft 22,, one end ofv these levers terminating in a smooth faced-plate 23a; levers 23 move in the extension of step 15 commencement openings 24 and in their lower position they occupy steps 15 and fully close openings 24,;and are in alignment with the table top plane (-FIG. 2); Furtherbackon table 3a are openings 25 through which locking levers 26 protrude above the table top level. Locking levers 26 swing on shaft 27 and their weighted ends 26a engage in notch 23b of lever'23. Eachrof'the guard elements '14,isprovidedwith an opening arm 23a and alock'lever 26.

With lock lever 26 engaging in notch 23b of lever 23 as shown onFIG. l, the opening lever end 23a extends upwards, locking guard element 14 inrthe upper, closed position. Movement of levers19 and Iguardelements 14 jointed thereto is limited in th e' lower position by limit stop 28 (FIG. 2). j

As shown on FIG. 1, 'thefassemblies consisting of guard elements 7 and '14 provide a double-guard covering over' elements 7 move freely and Between the openings 8, there' are comb tooth-like ribs, and dividing walls 8a which are joined together by.

1 only when this is held in the depressed position.

pushing workpiece 6 still further, it engages and depresses 4 operates only after being released by lock lever 26 and On to the levelof the table, a number of opening arms 23a correspondingto its own width, simultaneously lowering a similar number of-guard elements 14 below the table level by the agency of r0ds 23, 21 and 1?; on reaching 7 thej-feed edge of the table, the workpiece 6 assumes the position shown in FIG. 2, resting against the feed edge.

7 It will be seen from FIG. 2 that even after opening of the upper guard elementsa14,it is still impossible to touch theblade shaft by hand, as his fullycovered by the lower guard elements 7, which can only be displaced by pushing'the workpiece 6 further on with bothhands. In the 'event of the hands being removed or slipping from workpiece 6, the pressure applied to opening lever 23a ceases and then, without the lower guard elements 7 having moved and :opened the blade shaft 1, the upper guard elements 14 return to theirformer closed position above guard elements 7. This double guard position providing perfect protection against accidents is therefore maintained even during movement of workpiece 6 until it reaches the cutting blades, and however thin the workpiece is, it cannot become jammed under the guard elements.

As the workpiece 6 passes from the position shown on FIG. 2, it pushes before it a number of lower guard elements 7 corresponding to its own width thus opening the lower guard, but at the same time .it covers the blade shaft, and as the end of the workpiece proceeds beyond opening arm 23a, thistilts upwards and ceases to cover guard element14,simultaneouslypermitting this guard element to return to its upper guard position, by closing onto the end of the workpiece'as shown on FIG. 3, before it leaves table 3a' and the guard elements then follow the workpiece until they assume the fully closed position.

Accident protection is thus perfect, as the upper guard 14 cannot be turned backwards above the blade shaft 't-owards'open position due to the action of opening arm 23:1,; as when this is tilted upwards, arm 26a of lock lever 26 immediately engages into the locking notch of lever 23. :Protection remains perfect even in the event of the workpiece being jolted backwardsa frequent and dangerous occurrence in this positionas guard element 14 closely follows the end of the workpiece, and together with the locked lever 23 offers continuous resistance to backwards jolting of workpiece 6. Reference to FIG. 3

will also show 'th'at'even if workpiece6 is jolted in passblade shaft 1, extending over the whole table width of a the planing machine (FIG. 4) when the machineis used, only the number of guard elements corresponding to the width of the workpiece 6 become operative,,and open a corresponding part of the blade shaft. It will also be seen that the guards formed by the lower elements 7 resting over the bladeshaft, the ,operators hand cannot reach the blades, since the passing'of the workpiece end immediately frees lower guard elements 7 to return to their closing position, and the hand or hands slipping from a jolting workpiece will-come into contact with the upper guard elements '14 already in closing positionpand pressure of the hands on these guards is in the closing direc tion. x d

V In spite of the fact that the guard system described in the foregoing is made up of a series of piano key-like elements, these do 'not preventor hinder blade adjustments [or sharpening or even changing blade shaft 1, as a mechanical means is provided enabling the complete guard assemblies tobe opened inprder'to; expose the blade shaft. Angle levers 29 turning on shafts 30, engage with 'levers'l-l and 19. Angle levers 29 are actuated by screw ing against the edge of the feed table and the upper elements 14 arching above, provide complete protection,

they cannot be opened by hand and thus the blade shaft cannot be reached by hand, as not even with two hands I can they'be opened to cause an accident.

Thedevice described'in the-foregoing operates in the following manner, commencing from the position shown inFIG. 1. t

Workpiece 6 is pushed along table 3a in thedirectibn indicated by the arrow, thereby turning locklever; 26,; whose end 26a releases lever 23,; In proceeding over lock lever 26, workpiece 6 reaches opening arm.,23a, .which spindles 32 jointed to common shafts 31 which are threaded through one end of the angle levers 29; in this manner the angle ilevers depre'ssleversfl and 14, therebyturning and opening the complete assemblies of guard elements 7 andj14. '7

canfbe used to actuateseetions ofthe. guard assemblies. Thei novel method of iusing 'guardnelementsguided and the consequent disturbances or breakdowns.

by dividing ribs and placed side by side without gaps, is that it excludes the possibility of workpieces jamming This safety effect is enhanced by using the obliquely adjustable fence lath 5, and by lateral or oblique setting of this, the position of irregular widening or wedge shaped workpieces can be adjusted to the guard elements and suitably guided.

From the above description it follows that this guard equipment not only provides perfect protection but also maintains the protection in all operating phases, even in the case of breakdowns or unexpected situations arising due to machine or operators fault.

In order to achieve this perfection of protection and safety, numerous novel principle and constructional solutions and perfections are embodied in the invention, in addition to elimination of the faults of existing guard types, and the advantages and fault elimination effects of the invention are listed in the following:

(a) Actuation of the guard equipment requires no expenditure of energy,

(12) Operation of the guard system is simple and requires no additional work or attention on the part of the operator. This guard system does not hinder cutting work of the machine nor does it impede removal of chips from the machine,

(0) Most of the parts of the guard equipment are components of identical sizes suitable for standardization, and thus machines and tables of different sizes can be provided for by chosing the number of guard elements to be used,

(d) The individual components, eg the guard elements themselves, could be made of transparent plastic material by mass production methods, such as die forming, extrusion, thus being inexpensive to produce,

(e) The guard equipment can be subsequently fitted to any type of surface planing machine,

(f) Protection is perfected to such a degree that intentional injuries or self-mutilation cannot be inflicted,

(g) Each element of the guard is guided in the table tops, and resting on the table bottom and upon each other, together they form a sufficiently stiff and strong continuous protection cover to withstand denting and deformation,

(h) By means of suitable selection of the distance between the opening arm 2341 and lock lever 26, the minimum size of the workpiece can be determined in order to exclude the possibility of using short workpieces unsuitable for safe handling,

(i) While feeding the workpiece, opening arms 23a completely cover the work table surface and guard elements 14 in their position below the table level, thus pressure exerted on the workpiece does not reach the guard elements and they are protected from deformation,

(j) In the event of the workpiece being jolted backwards, it is arrested by lock lever 26 and thus remains on the table,

(k) The arm-like extensions of guard elements 7 do not face the direction of blade rotation and therefore cannot come into collision with the blades,

(1) The double covering afforded by the guard elements renders machine cleaning and the use of cleaning cloths a safe operation, even in the event of the machine having inadvertently been left running,

The principal advantage of the guard system forming this invention exceeding those listed above, is that it provides safety against the most dangerous of all accident causes, i.e. psychological factor causes; inasmuch as double protection is provided in all phases of working. The majority and the more series accidents occur when untoward working circumstances arise, i.e. a workpiece jolts backwards or jams, blade breakage etc., when the operator involuntarily directs his attention to the irregularity, and he is then liable to neglect his own safety. These occasions, and any position of the workpiece relative to the blade shaft, are when the guard equipment should provide full and automatic protection. This degree of safety is fully provided with the present equipment, as in the event of any unexpected situation whatsoever arising, whether a jolting workpiece or hands slipping from the workpiece, the guards effectively cover the blade shaft at all times.

What I claim is:

1. A guard and accident prevention equipment for planing machines of the Wood working industry, comprising a plurality of arched lower and upper guard elements respectively comprising comb like elements closing over the blade shaft from opposite sides thereof and tiltable to positions under the machine worktable, a plurality of opening levers located on the feed side of the blade shaft and similarly tiltable to under the worktable, said equipment further comprising a plurality of weight-loaded lock levers pivotally mounted to swing under their own weight into engagement with said opening levers, said lock levers being arranged prior to said opening levers in the feed path of the workpiece and being tiltable to positions under the worktable.

2. A guard and accident prevention equipment for planing machines of the wood working industry, comprising a plurality of arched lower and upper guard elements respectively comprising comb like elements closing over the blade shaft from opposite sides thereof and tiltable to positions under the machine worktable, a plurality of opening levers located on the feed side of the blade shaft and similarly tiltable to under the worktable, said equipment further comprising a plurality of weightloaded lock levers pivotally mounted to swing under their own weight into engagement with said opening levers, said lock levers being arranged prior to said opening levers in the feed path of the workpiece and being tiltable to positions under the worktable, said equipment further comprising a guiding rail mounted to the worktable at one edge thereof and extending parallel to the longitudinal axis of the worktable, said guarding rail being spaced from said guard elements, said opening levers and said lock levers and being adjustable laterally with respect to the protecting elements and fixable in any adjusted position.

3. An equipment as claimed in claim 2 in which all protecting elements of said equipment are provided with counterweights for automatically restoring the elements to their normal positions.

4. An equipment as claimed in claim 1 wherein a portion of the upper guard element of each pair overlies a portion of the mating lower guard element when the guard elements are in the closed position, the guard elements of each pair being in axial alignment and of substantially the same width.

References Cited by the Examiner UNITED STATES PATENTS 1,206,539 11/ 16 Hunsicker 144-251 1,829,313 10/31 Tompkins 144-251 2,506,610 5/50 Mueller 144-251 X FOREIGN PATENTS 379,653 9/ 3 2 Great Britain.

WILLIAM W. DY ER, JR., Primary Examiner.

DONALD R. SCI-IRAN, Examiner. 

1. A GUARD AND ACCIDENT PREVENTION EQUIPMENT FOR PLANING MACHINES OF THE WOOD WORKING INDUSTRY, COMPRISING A PLURALITY OF ARCHED LOWER AND UPPER GUARD ELEMENTS RESPECTIVELY COMPRISING COMB LIKE ELEMENTS CLOSING OVER THE BLADE SHAFT FROM OPPOSITE SIDES THEREOF AND TILTABLE TO POSITIONS UNDER THE MACHINE WORKTABLE, A PLURALITY OF OPENING LEVERS LOCATED ON THE FEED SIDE OF THE BLADE SHAFT AND SIMILARLY TILTABLE TO UNDER THE WORKTABLE, SAID EQUIPMENT FURTHER COMPRISING A PLURALITY OF WEIGHT-LOADED LOCK LEVERS PIVOTALLY MOUNTED TO SWING UNDER THEIR OWN WEIGHT INTO ENGAGEMENT WITH SAID OPENING LEVERS, SAID LOCK LEVERS BEING ARRANGED PRIOR TO SAID OPENING LEVERS IN THE FEED PATH OF THE WORKPIECE AND BEING TILTABLE TO POSITIONS UNDER THE WORKTABLE. 